Apparatus and methods to prevent biofouling

ABSTRACT

Techniques for reducing biofouling on optical equipment, using minimum power in a marine environment are provided. An example of an apparatus according to the disclosure includes a housing including a cavity and an ultraviolet transparent window disposed over the cavity, an optical device disposed in the cavity and directed towards the ultraviolet transparent window, one or more ultraviolet light emitting diodes disposed in the cavity and directed towards the ultraviolet transparent window, and a controller operably coupled to the one or more ultraviolet light emitting diodes and configured to provide at least one lamp power function to the one or more ultraviolet light emitting diodes, wherein the at least one lamp power function is based on at least a flash power value, a flash duration, a rest power value and a rest duration.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.62/559,971, filed Sep. 18, 2017, entitled “APPARATUS AND METHOD TOPREVENT BIOFOULING,” the entire contents of which is hereby incorporatedherein by reference.

BACKGROUND

The biofouling of materials used in marine environments has been aproblem to naval operations for millennia. Generally, “biofouling”refers to the accumulation of microorganisms, plants, algae, or animalson surfaces. Historically, methods to reduce or eliminate biofoulinginvolved the use of biocidal compounds in paints or other coatingsapplied to exposed surfaces. Such coatings wear off over time and aresubject to spallation, cracking and other imperfections, and are notsuitable for many applications.

More recently, an increasing number of optical sensors and cameras arebeing used to research the underwater environment. These sensors andcameras require windows that stay substantially clear and free frombiofouling for long periods of time without mechanical cleaning.Painting or coating the surface is not an option for this applicationbecause of the need for light passage through the windows.

The recent development of ultra violet (UV) light emitting diodes (UVLEDs), such as those comprising aluminum nitride, have made availablethe option to use generated UV light to kill microbes on and nearsurfaces to be protected against biofouling. There are commercialapparatuses on the market that irradiate underwater surfaces with UVlight, such as those described inHttp://www.amloceanographic.com/CTD-Sound-Velocity-Environmental-Instrumentation-Home/Biofouling.Another example of the use of UV light to prevent biofouling isdescribed in U.S. Pat. No. 9,235,048 and related US Publication No.2016/0121009, which are hereby incorporated by reference for allpurposes. Notably, most of the UV light sources used with theseapparatuses are situated outside of their housings, such that the lightsource is positioned in front of the window such that water is withinthe space between the light source and the window. As such, the lightsources may at least partly obstruct the view. Moreover, parts of thewindow may also be in the shade of mounting brackets used in theseapparatuses, and biofouling may still occur in these shadowed areas. Inaddition, the UV intensity may be attenuated by travelling through thewater. Finally, it is often challenging to deliver power to suchapparatuses in offshore underwater environments, and conventionalapparatuses are not generally designed to reduce power consumption. Assuch, one of the advantages of the present invention is to reducebiofouling through the effective delivery of UV light using minimalelectrical power.

SUMMARY

An example of a method for reducing biofouling in a marine environmentaccording to the disclosure includes disposing an optical device in themarine environment, wherein the optical device is directed at an objectin the marine environment, obtaining an image of the object with theoptical device, determining a quality of the image, determining a UVflash power value and a UV flash duration based on the quality of theimage, determining a rest power value and a rest duration based on thequality of the image, and activate at least one ultraviolet light sourcefor a plurality of cycles based on the flash power value, the flashduration, the rest power value and the rest duration, such that the atleast one ultraviolet light source is disposed proximate to the opticaldevice and directed at the object. As used herein, the term flash refersto a flash of UV light.

Many technical papers distinguish between UV power at the wavelength ofthe LED and the electrical power required to generate this UV power. Ingeneral, an electrical-to-UV-C conversion efficiency of 1% is attainedwith current LED technologies. In an effort to reduce ambiguity, powerspecifications used herein are labeled with electrical or UV units.

Implementations of such a method may include one or more of thefollowing features. At least one ultraviolet light source may becharacterized by emission wavelength of between 250 nanometers and 400nanometers. The flash duration may be between 0.01 seconds and 1000seconds. The flash power value may be between 1 milliwatt (UV) and 100milliwatts (UV). The rest power value may be less than 1 milliwatt. Therest duration may be between 1 second and 100,000 seconds. The flashpower value may be approximately 12.5 milliwatts (UV), the flashduration may be approximately 0.1 seconds, the rest power value may beless than 0.001 milliwatts, and the rest duration may be approximately19.9 seconds. Determining the quality of the image may be based on asharpness value associated with a contrast boundary in the image. Theflash power value, the flash duration, the rest power value and the restduration may be provided to a server. The flash power value, the flashduration, the rest power value and the rest duration may be receivedfrom a server.

An example of an apparatus for reducing biofouling in a marineenvironment according to the disclosure includes a housing including acavity and an ultraviolet transparent window disposed over the cavity,an optical device disposed in the cavity and directed towards theultraviolet transparent window, one or more ultraviolet light emittingdiodes disposed in the cavity and directed toward the ultraviolettransparent window, and a controller operably coupled to the one or moreultraviolet light emitting diodes and configured to provide at least onelamp power function to the one or more ultraviolet light emittingdiodes, wherein at least one lamp power function is based on at least aflash power value, a flash duration, a rest power value and a restduration. A lamp power function is the representation of the electricalpower applied to the UV LED over time.

Implementations of such an apparatus may include one or more of thefollowing features. The ultraviolet transparent window may beconstructed at least in part with at least one material selected from agroup consisting of sapphire, silicon carbide (SiC), diamond, zincsulfide (ZnS), zinc selenide (ZnSe), Barium fluoride (BaF2), aluminumdioxide (Al2O3), quartz (SiO2), and magnesium fluoride (MgF2). At leastone of the one or more ultraviolet light emitting diodes may becharacterized by emission wavelengths between 250 nanometer and 400nanometers. A power source may be operably coupled to the one or moreultraviolet light emitting diodes. The controller may be configured toreceive the at least one lamp power function from a remote server. Thecontroller may include at least one data structure configured to storethe at least one lamp power function. The flash duration may be between0.01 seconds and 1000 seconds and the flash power value may be between 1milliwatt (UV) and 100 milliwatts (UV). The rest power value may be lessthan 10 milliwatts and the rest duration may be between 1 second and100,000 seconds. The flash power value may be approximately 12.5milliwatts (UV), the flash duration is approximately 0.1 seconds, therest power value may be less than 0.001 milliwatts (UV), and the restduration is approximately 19.9 seconds.

An example of an apparatus according to the disclosure includes ahousing means including a cavity configured to enclose one or moreoptical device means and one or more ultraviolet light emitting means,an ultraviolet transparent window means disposed on the housing meansover the cavity, such that the one or more optical device means and theone or more ultraviolet light emitting means are directed towards theultraviolet transparent window means, and a controller means operablycoupled to the one or more ultraviolet light emitting means andconfigured to provide at least one lamp power function to the one ormore ultraviolet light emitting means, such that the at least one lamppower function is based on at least a flash power value, a flashduration, a rest power value and a rest duration.

Items and/or techniques described herein may provide one or more of thefollowing capabilities, as well as other capabilities not mentioned. Anoptical sensing device may be placed behind a window in a marineenvironment. The window may be a transparent or semi-transparentcomponent through which light is passed. An ultraviolet (UV) lightsource may be directed at the window. The UV light may impede the growthof marine algae on the window. A programmable controller may be operablycoupled to the UV light source and configured to cyclically activate theUV light source using two or more periods at varying power levels. Acycle may include a short high-power UV light flash, followed by arelatively longer period of relatively low power UV light or no UVlight. The cyclical operation may reduce the power consumed by thecontroller. The reduced power consumption may extend the operationalservice life of the optical sensing device. Other capabilities may beprovided and not every implementation according to the disclosure mustprovide any, let alone all, of the capabilities discussed. Further, itmay be possible for an effect noted above to be achieved by means otherthan that noted, and a noted item/technique may not necessarily yieldthe noted effect.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an example apparatus to prevent biofouling.

FIG. 2 is an example of a lamp duty cycle for the apparatus of FIG. 1.

FIG. 3 includes transmittance graphs for example UV transparent windows.

FIGS. 4A and 4B are example results of chlorophyll buildup andprevention.

FIG. 5 is an example process diagram for a method of determining a lampduty cycle.

DETAILED DESCRIPTION

Techniques are discussed herein for extending the service life ofoptical sensors in a marine environment. For example, an optical sensormay be disposed in an apparatus that includes a window used forunderwater applications. The container and window may be operable undera pressure of up to 10,000 m of water. A method to keep the windowsubstantially clear and free from biofouling includes using two or moreperiods of UV radiation with varying power. The sequence of theseperiods as defined by duration and UV power comprises a cycle. Incertain embodiments, a cycle repeats itself indefinitely. In anon-limiting example, one cycle may comprise a short, high power UVlight (i.e., a flash), followed by a relatively longer period ofrelatively lower power UV light or no UV light. As used herein, “window”refers to any transparent or semi-transparent component through whichlight is passed.

The optical sensor and window apparatus may be utilized in underwaterenvironments, such as underwater optical sensors, underwater cameras andunderwater lights. They may also be used to expose deep sea environmentsto UV light, where such light would otherwise never be found. Inaddition to being used for biocidal applications, the window apparatusmay be suitable for other related applications, such as curing materialsextruded into the deep-water environment and forming structures neededoutside of a vessel. Specifically, in certain embodiments, the apparatusmay use less than 20 mW electrical power (continuous), preferably lessthan 10 mW (electrical, continuous) and even more preferably less than 5mW (electrical, continuous). As used herein, continuous power refers tothe energy consumed during all periods of one entire cycle divided bythe duration of that entire cycle. These techniques are examples only,and not exhaustive.

Referring to FIG. 1, an example apparatus 100 to prevent biofouling isshown. In an example, the apparatus includes a housing 102, a UVtransparent window 104, a device cavity 106, one or more UV lightemitting diodes (LEDs) 108, an optical device 110, and a controller 112.The housing 102 may be a cylindrical housing that is open on one end.Other shapes and configurations may also be used. In general, thehousing 102 may be constructed from suitable materials to withstand anunderwater environment and corresponding mechanical forces to which itwill be subjected. The housing 102 includes the device cavity 106configured to accommodate one or more optical devices 110. The cavity106 may optionally be filled with dry air, substantially pure nitrogen,argon and/or other inert gas. The opening on the housing 102 is fittedwith a leak-tight window 104 comprising one or more UV-transparentmaterials. The housing 102 includes an internal arrangement of one ormore UV LEDs 108 configured to project light onto the window 104. In anexample, the UV LEDs 108 are characterized by emission wavelengths ofbetween 250-400 nm, preferably around 275 nm. In certain embodiments,individual UV LEDs 108 may be configured to emit the same or differentwavelengths in the same apparatus. The UV LEDs 108 are operably coupledto a power source (not shown in FIG. 1) and the controller 112. Powersource may be an internal source (e.g., a battery) or an external source(e.g., via a water-tight connector in the housing 102). Inductivecharging (e.g., wireless) techniques may also be used to charge theinternal battery.

The housing 102 further encloses one or more optical devices 110 andequipment as necessary for its application, such as a camera, an opticalsensor, a lamp or simply the UV LEDs 108 only. The spatial arrangementof the UV LEDs 108 can be used to control the UV intensity distributionin the water-facing surface of the window. The intensity distributioncan be designed depending on the intended use. For example, the UVintensity distribution is uniform across the window in some embodiments,while in other embodiments, the UV intensity is highest in the center ofthe window, while in still other embodiments, the UV intensity ishighest around the window annulus.

The UV LEDs 108 are configured to irradiate the UV transparent window104 from the inside of the housing 102. That is, the UV LEDs 108 areorientated in the same general direction as the optical device 110(e.g., both are directed toward an object). Additionally, in contrast toapparatuses of the prior art that project UV light from the outside ofassociated housings through water with attenuates UV light, the internalUV LED configurations of the present invention offer many advantagessuch as a reduction in energy consumption because UV light does nottravel through water. The internal UV LEDs do not require externalstructures to support a light source, which may protrude from theoutside surface of the housing and thus increase drag on an underwaterapparatus. Further, the window 104 may be made flush with the surface ofthe housing 102 and the UV LEDs 108 can be installed inside the samewatertight device cavity 106 that protects the optical devices 110(e.g., cameras and other components within the apparatus), thus reducingcomplexity.

Referring to FIG. 2, with further reference to FIG. 1, an example lampduty cycle graph 200 is shown. The graph 200 includes a lamp power axis202, a time axis 204 and a lamp power function 206. The UV LEDs 108is/are driven by controller 112 that is configured to apply a timedsequence of power to the UV LEDs 108. The timed sequence may be a lamppower function 206 that includes a number of periods of varying powerand duration, i.e., a complete cycle. In certain embodiments, thesequence is a period of relatively higher power 206 a followed by aperiod of relatively lower power 206 b, as schematically depicted inFIG. 2. The duration of the higher power period (e.g., duty period,flash) may be in a range from 0.01 seconds to 1,000 seconds. As anexample, and not a limitation, the power applied during the duty periodmay be between 0.01× and 10.0× of the maximum rated continuous output ofthe UV LEDs 108, and the duration of the lower power period (“restperiod”) may range from 1 second to 100,000 seconds. The cycleprofile—or the sequence of periods—may be tailored for specific marinebiofouling environments. In an example, the power applied during therest cycle is between 0.001× and 1.0× of the maximum rated continuousoutput of the LED. Commercially available UV LEDs (e.g., Klaran LED byCrystal-IS) may be rated at a maximum power of approximately 4 W(electrical, continuous). In an example, the controller 112 may beconfigured to provide a power function to each of the UV LEDs 108individually, as a group, or combinations therein. The controller 112may be configured to supply different lamp power functions to differentUV LEDs 108 or different groups of UV LEDs 108.

Some effects of the interaction of the UV light with water are known tobe biocidal (e.g. formation of ozone and hydrogen peroxide). The UV LEDs108 generate(s) a high intensity of UV light energy at the window 104surface in contact with seawater, thus producing a high concentration ofbiocidal chemical agents on and near the window surface.

In an embodiment, the UV transparent window 104 may be comprised ofspecialty window materials, which work together with the UV light tolower the UV dosage required for biofouling reduction or elimination.Such embodiments make use of windows that are substantially opticallyclear but have outer surfaces that are modified to contain atoms orcompounds of metals such as silver, copper, tin and/or lead. The UV LEDs108 activates biocidal effects in these metals, which do not leach intosurrounding water. Thus, there is no environmental damage and nodeterioration of the effect over time. In other embodiments, thewater-facing surface of the window may be mechanically modified toprovide additional anti-biofouling properties; such as, for example,being engraved with a micro pattern of a periodicity of 500 to 10,000nm.

The controller 112 may include one or more processors and associatedmemory devices configured to provide a voltage signal to the UV LEDs108. For example, the controller 112 may include a micro control unit(MCU) like an Attiny-85 by Microchip and suitable electronic componentsto control different temporal patterns and UV power settings toestablish multiple irradiation modes for one or more UV LEDs 108.Example modes include continuous and pulsed UV irradiation. Under bothsuch modes, the UV power can be selected. For example, flash intensityand duration values may be determined based on the marine environment.Similarly, rest intensity and duration values may be determined. Theintensity and duration values may vary cycle to cycle and need not beconstant (i.e., sinusoidal, sawtooth or other signal profiles may beused for the flash and rest periods). This allows adjustment forimproved anti-biofouling results and energy economy. For example, pulsedirradiation with very high intensity pulses for short periods to use thelowest possible electrical power or as a special case where duty powerand rest power are equal (e.g., continuous irradiation at intensitylevels that prevent biofouling but still minimize the electrical powerthat is consumed). The controller 112 may be internal to the housing orexternal and coupled to the UV LEDs 108 via a waterproof coupler (notshown in FIG. 1).

The controller 112 may be configured to provide control for both thepower and timing of all UV LEDs 108 individually or collectively. Theapparatus may comprise several UV LEDs 108 of different wavelengths. Thecontroller 112 may be configured to provide each individual UV LED 108with its own individual control signal to enable a temporal lightpattern.

In an example, the materials used to make the housing 102 may beelectrically conductive, in which case the housing 102 can be used as anelectrode for the UV LEDs 108. Example materials for the housing 102include, but are not limited to, stainless-steel, copper, biocidallytreated PVC, ABS and PE, ceramics such as SiN, Al2O3, BN, porcelain,glass and fiberglass. These materials may be treated to minimizebiofouling, such as by coating or integration of anti-biofoulingmaterials. For example, a stainless-steel housing could be copper clad.Polymer materials may be infused with nanoparticles that are known toprevent biofouling. Other anti-fouling techniques may also be used onthe exterior surface of the housing 102.

Referring to FIG. 3, transmittance graphs of example UV transparentwindows is shown. The UV transparent window 104 may be constructed frommaterials such as, for example, sapphire, silicon carbide (SiC),diamond, zinc sulfide (ZnS), zinc selenide (ZnSe), Barium fluoride(BaF2), aluminum dioxide (Al2O3), quartz (SiO2), magnesium fluoride(MgF2), and other UV transparent materials. In an example, the UVtransparent window 104 may be a composite of different materials such asthe result of chemical or plasma vapor deposition process. Thetransmission properties of some of these materials are graphicallyillustrated in FIG. 3. A first graph 302 illustrates the transmittanceversus wavelength for Barium Fluoride. A second graph 304 illustratesthe transmittance versus wavelength for Silicon Dioxide. A third graph306 illustrates the transmittance versus wavelength for MagnesiumFluoride. A fourth graph 308 illustrates the transmittance versuswavelength for Sapphire. A combination of these materials and/ormultiple windows may be required for requisite mechanical strength fordeep sea applications. Generally, the embodiments of the UV transparentwindow 104 are characterized by mechanical strengths suitable for waterpressures from 0 to 100 MPa (0-10,000 m water column). Thick windowsfrom water soluble material like MgF2 with high UV transparency andadequate mechanical strength may be combined with a thin sapphire orquartz protective window. In an example, a hydrophobic coating (e.g.,Al2O3) may be applied to the exterior of the UV transparent window 104to help reduce biofouling. In an example, the exterior coating on the UVtransparent window 104 may be the result of an atomic layer depositionprocess to produce an atomically smooth surface in an effort to reducebiofouling on the exterior surface.

Referring to FIG. 4A, with further reference to FIGS. 1 and 2, exampleresults of chlorophyll buildup and prevention are shown. A first testresults graph 400 includes a fluorescence axis 402, a light wavelengthaxis 404, a first control curve 406, and a results curve 408. Thefluorescence axis 402 is expressed in arbitrary units to show thefluorescence emission intensity of chlorophyll buildup on a controlwindow in an underwater marine environment. In an example, the apparatus100 may be used as a fouling resistant fluorometer. That is, the opticalsensor 110 may be configured to measure the fluorescence of seawater andthe control curve 406 and the results curve 408 represent measure offluorescence at the indicated wavelengths. The control curve 406 showsthe results of a window placed in a marine environment that was notirradiated by a UV source. The control curve 406 indicates the formationof chlorophyll (e.g., the appearance of the chlorophyll emission) on thecontrol window material. The formation of chlorophyll is an earlyindicator for the onset of biofouling, because biofouling communitiesinclude algae and cyanobacteria that produce chlorophyll. In comparison,the results curve 408 illustrates the results of illuminating anidentical window in the same marine environment as the control windowwith the UV LEDs 108. The results curve 408 indicates the absence ofchlorophyll formation on the window that was irradiated with 40 mW (285UV) (400 mA) for 0.1 sec—the flash intensity and duration 206 a—followedby darkness (or 10e-12 mW for the low intensity cycle) for 19.9 sec—therest intensity and duration 206 b. Summation of the energies used duringthe periods and division by the sum of durations of the periods providesthe equivalent of 200 microwatt—of 285 UV continuous or—considering anelectrical to UV conversion efficiency of 1% of state-of-the-art UVLEDs—20 mW electrical continuous.

Referring to FIG. 4B, with further reference to FIGS. 1 and 2, exampleresults of chlorophyll buildup and prevention are shown. A second testresults graph 420 includes the fluorescence axis 402, the lightwavelength axis 404, a second control curve 422, a 5-microwatt resultscurve 424, and a 12.5-microwatt results curve 426. The control curve 422shows the results of a window placed in a marine environment that wasnot irradiated by a UV source. The control curve 422 indicates theformation of chlorophyllon the control window material. (by theappearance of the chlorophyll emissionspectrum) The 5-microwatt resultscurve 424 and the 12.5-microwatt results curve 426 illustrates theresults of illuminating an identical window in the same marineenvironment as the control window with the UV LEDs 108. The 5-microwattcontinuous (averaged) results curve 424 indicates a relatively lessamount of chlorophyll formation on a window that was irradiated with 1mW (285 UV) (10 mA current) for 0.1 sec (e.g., the flash intensity andduration 206 a), followed by darkness (or 10e-12 mW for the lowintensity cycle) for 19.9 sec (e.g., the rest intensity and duration 206b). The 12.5-microwatt continuous (averaged) results curve 426 indicatesno amount of chlorophyll formation on a window that was irradiated withapproximately 2.5 mW (285 UV) (25 mA current) for 0.1 sec followed bydarkness of 19.9 sec, or 12.5 μW integrated UVC. The 12.5-microwattresults curve 426 illustrates that a virtual elimination of biofoulingmay be achieved with much less power as required by other light-basedbiofouling solutions and as expected by those skilled in the art. Theflash and rest intensity and duration values are examples only as othervalues may be used based on the marine environment and operationalapplication of the apparatus 100.

Referring to FIG. 5, with further reference to FIGS. 1-4B, a method 500of determining a lamp duty cycle includes the stage shown. The method500 is, however, an example only and not limiting. The method 500 may bealtered, e.g., by having stages added, removed, rearranged, combined,performed concurrently, and/or having single stages split into multiplestages. For example, stages 508 and 510 for determining the flash andrest intensity and duration values may be combined into a single stage.Still other alterations to the method 500 as shown and described arepossible.

At stage 502, the method includes disposing an optical device in amarine environment, such that the optical device is directed at anobject in the marine environment. The optical device 110 may be locatedwithin the device cavity 106 in the housing 102 and behind the UVtransparent window 104. In an example, the optical device 110 may becapable of movement within the cavity 106 thus optical device 110 may bedirected along a different axis than the housing 102. The housing 102may include multiple UV transparent windows 108 at differentorientations (e.g., on different planes) and the optical device 110 maybe configured to align with each of the different orientation to obtainan image through the windows. The object in the marine environment maybe a visual test pattern, quick response code, bar code, or other objectwith known dimensions or visual features. In an example, the object maybe a reflector or a constant light source. In some installations, theobject may be part of the environment such as a coral formation, or aman-made object such as an anchor chain or cable. In general, the objectis used as a reference to compare image quality over a period of time.

At stage 504, the method includes obtaining an image of the object withthe optical device. The optical device 110 may be a camera or othersensor configured to obtain and store an electronic representation ofthe object. The representation of the object may be stored in a memorywithin the optical device 110, the controller 112, or other devicewithin or external to the housing 102. In an example, the image maypersist in a computerized file formats such as raw formats (e.g., cameraimage file format (CIFF), digital negative (DNG), etc.), raster formats(e.g., joint photographic experts group (JPEG), tagged image file format(TIFF), graphics interchange format (GIF), bitmap (BMP), portablenetwork graphics (PNG), etc.), stereo formats (e.g., portable networkgraphics (PNS), multi picture object (MPO), etc.), or other electronicformats that are suitable for use in objective image quality algorithms.

At stage 506, the method includes determining a quality of the image.The controller 112, or other computer system, may be configured toexecute one or more objective methods to determine a quality of theimage obtained at stage 504. For example, full-reference andreduced-reference methods may be used based on a previously obtained orstored image of the object. No-reference methods may also be used todetermine the quality of image without reference to a prior image. Thequality of the image may be based on a sharpness value associated withcontrast boundaries in an image. Example of image sharpness qualitymeasures include cumulative probability detection (CPBD) and justnoticeable blur (JNB). The image quality measure may be based on afrequency domain image blur measure. Other objective image qualityalgorithms may be used to determine a quality of the image of theobject. The quality of the image may be compared to a previouslydetermined threshold value to determine whether or not the image qualityis operationally acceptable. That is, a low-quality image may be anindication of a potential increase in biofouling on the exterior surfaceof the UV transparent window 104. The image quality may be used tomodify the control signal provided to the UV LEDs 108.

At stage 508, the method includes determining a flash intensity valueand a flash duration based on the quality of the image. The controller112, or other computer system, may be configured to modify the powersignal provided to the UV LEDs 108. In an example, a look-up table orother data structure may include one or more tables to correlate one ormore image quality values with flash intensity and duration values(e.g., the period of relatively higher power 206 a). For example, inresponse to a low-quality image obtained at stage 504, the controller112 may increase the intensity value of the flash (e.g., provide ahigh-power flash), increase the duration of flash (e.g., a longer activetime), or a combination of both. In an example, the flash intensityvalue may be between 10 mW and 100 mW, and the flash duration may bebetween 0.01 seconds and 1000 seconds.

At stage 510, the method includes determining a rest intensity value anda rest duration based on the quality of the image. The controller 112,or other computer system, may be configured to modify the power signalprovided to the UV LEDs 108. In an example, a look-up table or otherdata structure may include one or more tables to correlate one or moreimage quality values with rest intensity and duration values (e.g., theperiod of relatively lower power 206 b). For example, in response to alow-quality image obtained at stage 504, the controller 112 may increasethe intensity value of the rest power (e.g., provide a lower rest lampintensity), decrease the duration of rest period (e.g., increase therate of flashes), or a combination of both. In an example, a look-uptable or other function may be used to determine a combination of flashintensity, flash duration, rest intensity and rest duration (e.g., thelamp power function 206) based on the image quality. The lamp powerfunction 206 need not be limited to impulse signals (e.g., flashes) asother power profiles may be used (e.g., stepped functions, saw-tooth,quick pulses, etc.). The lamp power function 206 may be based on morethan one image quality calculation. For example, multiple image qualitycalculations may be used to determine a rate of image qualitydegradation, and the lamp power function 206 may be based on the rate ofimage quality degradation. The objective of changing the lamp powerfunction 206, including the flash and rest periods, is to retard therate of biofouling and/or possibly reduce the amount of accumulatedbiofouling.

At stage 512, the method includes activating at least one ultravioletlight source for a plurality of cycles based on the flash intensityvalue, the flash duration, the rest intensity value, and the restduration, wherein the ultraviolet light source is disposed proximate tothe optical device and directed at the window. The controller 112 isconfigured to provide one or more lamp power functions 206 to one ormore of the UV LEDs 108 disposed within the cavity 106. The UV LEDs 108are directed toward the UV transparent window 104 and thus in thedirection of the object. The proximity of the UV LEDs 108 to the opticaldevice 110 and the UV transparent window 104 enables a reduction of lamppower to achieve a reduction in biofouling as compared to externallymounted lamps because the emitted UV energy is not absorbed byintervening seawater. The number of cycles may be based on an expectedresults time period. For example, the UV LEDs 108 may be activated basedon the determined flash intensity value, the flash duration, the restintensity value, and the rest duration for a period of minutes, hours,days, weeks. After a plurality of cycles, the method includes obtaininganother image at stage 504 and iterating through the method 500 again.In an example, the optical device 110 may be configured to enter a darkmode (e.g., not active) or a shutter down mode (e.g., closing theoptical path) when the UV LEDs 108 are activated.

In an example, the apparatus 100 may be included in a network includinga plurality of similar apparatuses. The network may include opticaldevices in a relatively small operational area (e.g., harbor, offshoreoil rig) or a larger network (e.g., ocean region). Each of theapparatuses 100 may be configured to send and receive lamp powerfunctions 206 to one or more network servers/data storage devices. In anexample, the controller 112 may include a communication moduleconfigured to send and receive wired or wireless communication packets(e.g., ethernet, WiFi, BLUETOOTH, near-field communication technologies,infra-red, UV, and visible light communication, etc.). In such anetworked environment, the lamp power functions 206 may be crowdsourcedsuch that particularly effective lamp power functions 206 determined onone apparatus may be stored on one or more networked servers and thenpropagated to other devices on the network. An effective lamp powerfunction 206 may be evaluated based on a steady or slowly decreasingimage quality. The effectiveness of a particular lamp power function 206may be evaluated based on the geographic location of the reportingapparatus (i.e., some lamp power functions may be more effective incertain areas). The design of the apparatus 100 enables the transfer ofpower lamp functions across a network of similar system because the UVLED 108 is located within the cavity 106 for each apparatus 100 in thenetwork. That is, the present design reduces the possibility ofnon-linear effects caused by the seawater located between a window andUV source as may occur in the prior art.

Other examples and implementations are within the scope and spirit ofthe disclosure and appended claims. For example, due to the nature ofsoftware and computers, functions described above can be implementedusing software executed by a processor, hardware, firmware, hardwiring,or a combination of any of these. Features implementing functions mayalso be physically located at various positions, including beingdistributed such that portions of functions are implemented at differentphysical locations.

Also, as used herein, “or” as used in a list of items prefaced by “atleast one of” or prefaced by “one or more of” indicates a disjunctivelist such that, for example, a list of “at least one of A, B, or C,” ora list of “one or more of A, B, or C,” or “A, B, or C, or a combinationthereof” means A or B or C or AB or AC or BC or ABC (i.e., A and B andC), or combinations with more than one feature (e.g., AA, AAB, ABBC,etc.).

As used herein, unless otherwise stated, a statement that a function oroperation is “based on” an item or condition means that the function oroperation is based on the stated item or condition and may be based onone or more items and/or conditions in addition to the stated item orcondition.

Further, an indication that information is sent or transmitted, or astatement of sending or transmitting information, “to” an entity doesnot require completion of the communication. Such indications orstatements include situations where the information is conveyed from asending entity but does not reach an intended recipient of theinformation. The intended recipient, even if not actually receiving theinformation, may still be referred to as a receiving entity, e.g., areceiving execution environment. Further, an entity that is configuredto send or transmit information “to” an intended recipient is notrequired to be configured to complete the delivery of the information tothe intended recipient. For example, the entity may provide theinformation, with an indication of the intended recipient, to anotherentity that is capable of forwarding the information along with anindication of the intended recipient.

Substantial variations may be made in accordance with specificrequirements. For example, customized hardware might also be used,and/or particular elements might be implemented in hardware, software(including portable software, such as applets, etc.), or both. Further,connection to other computing devices such as network input/outputdevices may be employed.

The terms “machine-readable medium” and “computer-readable medium,” asused herein, refer to any medium that participates in providing datathat causes a machine to operate in a specific fashion. Using a computersystem, various computer-readable media might be involved in providinginstructions/code to processor(s) for execution and/or might be used tostore and/or carry such instructions/code (e.g., as signals). In manyimplementations, a computer-readable medium is a physical and/ortangible storage medium. Such a medium may take many forms, includingbut not limited to, non-volatile media and volatile media. Non-volatilemedia include, for example, optical and/or magnetic disks. Volatilemedia include, without limitation, dynamic memory.

Common forms of physical and/or tangible computer-readable mediainclude, for example, a floppy disk, a flexible disk, hard disk,magnetic tape, or any other magnetic medium, a CD-ROM, any other opticalmedium, any other physical medium with patterns of holes, a RAM, a PROM,EPROM, a FLASH-EPROM, any other memory chip or cartridge, a carrier waveas described hereinafter, or any other medium from which a computer canread instructions and/or code.

Various forms of computer-readable media may be involved in carrying oneor more sequences of one or more instructions to one or more processorsfor execution. Merely by way of example, the instructions may initiallybe carried on a magnetic disk and/or optical disc of a remote computer.A remote computer might load the instructions into its dynamic memoryand send the instructions as signals over a transmission medium to bereceived and/or executed by a computer system. The apparatus 100 may beoperably coupled to one or more processors via a wired and/or wirelessconnections.

The methods, systems, and devices discussed above are examples. Variousconfigurations may omit, substitute, or add various procedures orcomponents as appropriate. For instance, in alternative configurations,the methods may be performed in an order different from that described,and that various steps may be added, omitted, or combined. Also,features described with respect to certain configurations may becombined in various other configurations. Different aspects and elementsof the configurations may be combined in a similar manner. Also,technology evolves and, thus, many of the elements are examples and donot limit the scope of the disclosure or claims.

Specific details are given in the description to provide a thoroughunderstanding of example configurations (including implementations).However, configurations may be practiced without these specific details.For example, well-known circuits, processes, algorithms, structures, andtechniques have been shown without unnecessary detail in order to avoidobscuring the configurations. This description provides exampleconfigurations only, and does not limit the scope, applicability, orconfigurations of the claims. Rather, the preceding description of theconfigurations provides a description for implementing describedtechniques. Various changes may be made in the function and arrangementof elements without departing from the spirit or scope of thedisclosure.

Also, configurations may be described as a process which is depicted asa flow diagram or block diagram. Although each may describe theoperations as a sequential process, some operations may be performed inparallel or concurrently. In addition, the order of the operations maybe rearranged. A process may have additional stages or functions notincluded in the figure. Furthermore, examples of the methods may beimplemented by hardware, software, firmware, middleware, microcode,hardware description languages, or any combination thereof. Whenimplemented in software, firmware, middleware, or microcode, the programcode or code segments to perform the tasks may be stored in anon-transitory computer-readable medium such as a storage medium.Processors may perform one or more of the described tasks.

Components, functional or otherwise, shown in the figures and/ordiscussed herein as being connected, coupled (e.g., communicativelycoupled), or communicating with each other are operably coupled. Thatis, they may be directly or indirectly, wired and/or wirelessly,connected to enable signal transmission between them.

Having described several example configurations, various modifications,alternative constructions, and equivalents may be used without departingfrom the spirit of the disclosure. For example, the above elements maybe components of a larger system, wherein other rules may takeprecedence over or otherwise modify the application of the invention.Also, a number of operations may be undertaken before, during, or afterthe above elements are considered. Accordingly, the above descriptiondoes not bound the scope of the claims.

“About” and/or “approximately” as used herein when referring to ameasurable value such as an amount, a temporal duration, and the like,encompasses variations of ±20% or ±10%, ±5%, or +0.1% from the specifiedvalue, as appropriate in the context of the systems, devices, circuits,methods, and other implementations described herein. “Substantially” asused herein when referring to a measurable value such as an amount, atemporal duration, a physical attribute (such as frequency), and thelike, also encompasses variations of ±20% or ±10%, ±5%, or +0.1% fromthe specified value, as appropriate in the context of the systems,devices, circuits, methods, and other implementations described herein.

A statement that a value exceeds (or is more than or above) a firstthreshold value is equivalent to a statement that the value meets orexceeds a second threshold value that is slightly greater than the firstthreshold value, e.g., the second threshold value being one value higherthan the first threshold value in the resolution of a computing system.A statement that a value is less than (or is within or below) a firstthreshold value is equivalent to a statement that the value is less thanor equal to a second threshold value that is slightly lower than thefirst threshold value, e.g., the second threshold value being one valuelower than the first threshold value in the resolution of a computingsystem.

Further, more than one invention may be disclosed.

The invention claimed is:
 1. A method for reducing biofouling in amarine environment, comprising: disposing an optical device in themarine environment, wherein the optical device is directed at an objectin the marine environment; obtaining an image of the object with theoptical device; determining a quality of the image; determining a flashpower value and a flash duration based on the quality of the image;determining a rest power value and a rest duration based on the qualityof the image; and activate at least one ultraviolet light source for aplurality of cycles based on the flash power value, the flash duration,the rest power value and the rest duration, wherein the at least oneultraviolet light source is disposed proximate to the optical device anddirected at the object.
 2. The method of claim 1 wherein the at leastone ultraviolet light source is characterized by emission wavelength ofbetween 250 nanometers and 400 nanometers.
 3. The method of claim 1wherein the flash duration is between 0.01 seconds and 1000 seconds. 4.The method of claim 1 wherein the flash power value is between 1milliwatt and 100 milliwatts.
 5. The method of claim 1 wherein the restpower value is less than 1 milliwatt.
 6. The method of claim 1 whereinthe rest duration is between 1 second and 100,000 seconds.
 7. The methodof claim 1 wherein the flash power value is approximately 12.5milliwatts, the flash duration is approximately 0.1 seconds, the restpower value is less than 0.001 milliwatts, and the rest duration isapproximately 19.9 seconds.
 8. The method of claim 1 wherein determiningthe quality of the image is based on a sharpness value associated with acontrast boundary in the image.
 9. The method of claim 1 furthercomprising providing the flash power value, the flash duration, the restpower value and the rest duration to a server.
 10. The method of claim 1further comprising receiving the flash power value, the flash duration,the rest power value and the rest duration from a server.
 11. Anapparatus for reducing biofouling in a marine environment, comprising: ahousing including a cavity and an ultraviolet transparent windowdisposed over the cavity; an optical device disposed in the cavity anddirected towards the ultraviolet transparent window; one or moreultraviolet light emitting diodes disposed in the cavity and directedtoward the ultraviolet transparent window; and a controller operablycoupled to the one or more ultraviolet light emitting diodes andconfigured to provide at least one lamp power function to the one ormore ultraviolet light emitting diodes, wherein the at least one lamppower function is based on at least a flash power value, a flashduration, a rest power value and a rest duration.
 12. The apparatus ofclaim 11 wherein the ultraviolet transparent window is constructed atleast in part with at least one material selected from a groupconsisting of sapphire, silicon carbide (SiC), diamond, zinc sulfide(ZnS), zinc selenide (ZnSe), Barium fluoride (BaF2), aluminum dioxide(Al2O3), quartz (SiO2), and magnesium fluoride (MgF2).
 13. The apparatusof claim 11 wherein at least one of the one or more ultraviolet lightemitting diodes are characterized by emission wavelengths between 250nanometer and 400 nanometers.
 14. The apparatus of claim 11 furthercomprising a power source operably coupled to the one or moreultraviolet light emitting diodes.
 15. The apparatus of claim 11 whereinthe controller is configured to receive the at least one lamp powerfunction from a remote server.
 16. The apparatus of claim 11 wherein thecontroller includes at least one data structure configured to store theat least one lamp power function.
 17. The apparatus of claim 11 whereinthe flash duration is between 0.01 seconds and 1000 seconds and theflash power value is between 1 milliwatt and 100 milliwatts.
 18. Theapparatus of claim 11 wherein the rest power value is less than 1milliwatt and the rest duration is between 1 second and 100,000 seconds.19. The apparatus of claim 11 wherein the flash power value isapproximately 12.5 milliwatts, the flash duration is approximately 0.1seconds, the rest power value is less than 0.001 milliwatts, and therest duration is approximately 19.9 seconds.
 20. An apparatus,comprising: a housing means including a cavity configured to enclose oneor more optical device means and one or more ultraviolet light emittingmeans; an ultraviolet transparent window means disposed on the housingmeans over the cavity, wherein the one or more optical device means andthe one or more ultraviolet light emitting means are directed towardsthe ultraviolet transparent window means; and a controller meansoperably coupled to the one or more ultraviolet light emitting means andconfigured to provide at least one lamp power function to the one ormore ultraviolet light emitting means, wherein the at least one lamppower function is based on at least a flash power value, a flashduration, a rest power value and a rest duration.